how to change itunes back to how it was before updating?

This is a very vague request. What do you mean like it was before? If you want it 100% as before restore from the backup clone you made before installing unfamiliar software. If something went wrong with the library you can try:

ASC user turingtest2 help document: Empty/corrupt iTunes library after upgrade/crash - https://discussions.apple.com/docs/DOC-6561

If you don't see your content after updating iTunes - https://support.apple.com/kb/HT203225

Otherwise I am done guessing for now

in iTunes - https://discussions.apple.com/thread/7113829?answerId=28515130022#28515130022 "iTunes > Preferences > General > disable the Show Apple Music option. It basically hides all the new features of v.12.2.

To get rid of the cloud column. Go to music then click View in the menu bar and select Only Music Available Offline. Then go to movies click View select Only Movies Available Offline. Then TV Shows same thing View select Only TV Shows Available Offline. If you do all three of those that column will disappear.